Visiting from San Diego, Brian Ballestamon had the Culture Bus all to himself as he rode from Union Square to the Academy of Sciences in San Francisco, Calif., on Wednesday, Jan. 14, 2009. Muni launched the Culture Bus in the Fall of 2008 as a convenient way for visitors to hop on and off at several museums for a $7 all-day fare.

Photo: Paul Chinn, The Chronicle

Visiting from San Diego, Brian Ballestamon had the Culture Bus all...

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Painted in bright yellow, a Muni Culture Bus pulls up to a bus stop at the Museum of Modern Art in San Francisco, Calif., on Wednesday, Jan. 14, 2009. Muni launched the Culture Bus in the Fall of 2008 as a convenient way for visitors to hop on and off at several museums for a $7 all-day fare.

Photo: Paul Chinn, The Chronicle

Painted in bright yellow, a Muni Culture Bus pulls up to a bus stop...

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John Jiang drives an inbound Culture Bus on Oak Street in San Francisco, Calif., on Wednesday, Jan. 14, 2009. Jiang, a bus driver for the past six years, loves driving the route launched by Muni in the Fall of 2008 as a convenient way for visitors to hop on and off at several museums for a $7 all-day fare.

Photo: Paul Chinn, The Chronicle

John Jiang drives an inbound Culture Bus on Oak Street in San...

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A designated Culture Bus stop at the Museum of Modern Art is seen in San Francisco, Calif., on Wednesday, Jan. 14, 2009. Muni launched the Culture Bus in the Fall of 2008 as a convenient way for visitors to hop on and off at several museums for a $7 all-day fare.

Photo: Paul Chinn, The Chronicle

A designated Culture Bus stop at the Museum of Modern Art is seen...

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Brian Ballestamon (left) gets off a Culture Bus at the Academy of Sciences in Golden Gate Park in San Francisco, Calif., on Wednesday, Jan. 14, 2009. Muni launched the Culture Bus in the Fall of 2008 as a convenient way for visitors to hop on and off at several museums for a $7 all-day fare.

San Francisco's experimental CultureBus that caters to museum hoppers has drawn far fewer riders than envisioned when it launched in September, adding financial strain to the city's chronically cash-strapped transit system.

The special route shuttles people in bright yellow buses between the Yerba Buena arts district and Golden Gate Park's museums, with stops in Union Square and Civic Center. Despite the meager ridership, the premium-priced public transit service has strong backing in the cultural community, tourist industry and mayor's office.

"It is something that we want to see continued. It provides our visitors with a good alternative," said Stephanie Stone, spokeswoman for the California Academy of Sciences, which gives $3 ticket discounts for people who take transit to the new Golden Gate Park building.

As for Muni, agency officials say the 74X-CultureBus line, with exceptionally clean coaches and drivers who went through extra customer service training, can be a model for the rest of the city's transit system. It also could be used as an argument that people - tourists and Muni regulars - may be willing to pay a higher fare for better service.

That last point was brought home one recent afternoon when Cindy Pu, a nurse at St. Luke's Hospital in the Mission District, was rushing to get from Golden Gate Park to her late afternoon shift.

Unable to catch a cab, she was desperate to get to BART, which would put her within walking distance of the hospital. She could have taken one of several regular Muni lines to get to a BART station at a cost of $1.50, the regular cash fare. But she made the decision to pay $7 for the CultureBus, which got her close to the Civic Center BART Station in 20 minutes because it doesn't have other stops.

"I just can't take the chance catching a regular bus. You don't know when it will show up or how long it will take," Pu said.

Last year, Muni officials - on their perennial hunt for more money - proposed a surcharge on its express service. It never got past the idea stage.

$7 fare no obstacles for one tourist

Brian Ballestamon, a nurse visiting from San Diego, boarded a CultureBus on Wednesday afternoon at the Union Square stop for a ride to the Academy of Sciences. With the exception of a Chronicle reporter and photographer and the driver, the bus was empty. Ballestamon didn't blink at sliding $7 into the fare box.

"I'm on vacation," he said. "I really don't mind paying."

No one else boarded for the rest of the trip to Golden Gate Park. That's not unusual.

Ballestamon's driver, John Jiang, said the buses operate with few passengers much of the time.

The route takes six buses and five drivers out of regular Muni service - a luxury for the agency that always struggles to find enough drivers and working vehicles to meet all its scheduled runs systemwide.

The CultureBus has averaged 255 weekday boardings since service began the last week of September. Saturdays average 334 boardings; 215 on Sundays. The number of riders is probably much lower because the CultureBus ticket is good for unlimited boardings during a single day.

The new line launched as Muni was crafting a plan to shed or scale back underperforming lines in the city and shift drivers and buses to busier routes. That plan, called the Transit Effectiveness Project, is set to be phased in starting July 1.

Muni, faced with a deficit of at least $90 million over the next 18 months, had budgeted $1.6 million for a one-year CultureBus pilot project.

The revamped schedule, which begins Saturday, will run buses hourly instead of every 20 minutes. It will use two drivers instead of five and three buses instead of six. One of the buses will be used as a backup in case another breaks down. The change will save the agency an estimated $652,000 through the remainder of the yearlong experiment.

Muni chief Nathaniel Ford said he doesn't regret starting the CultureBus, saying it gave the agency the chance to test a specialized service and to see how quickly the bureaucracy could make adjustments based on ridership demand and fiscal reality.

"We've been able to be creative and take a little bit of risk," he said.

Politically, the agency didn't have much choice.

The whole notion of starting the bus line didn't go through normal channels but was pushed by the Academy of Sciences as it prepared for its grand reopening in September. Mayor Gavin Newsom's office helped usher in the plan.

Traffic jams around Academy of Sciences

Nevertheless, the wild popularity of the rebuilt museum has resulted in traffic jams and a parking shortage, particularly on weekends and holidays, while the CultureBus often arrives and departs from there nearly empty.

"It certainly got off to a slower start than we anticipated," said Geraldine O'Brien, director of arts and culture for the San Francisco Convention & Visitors Bureau.

Visiting museums, she said, is a favorite activity of tourists in the city. Offering people a simple way to get from one institution to another has its benefits, boosters say.

O'Brien suspects the bus will catch on once more people learn of its existence, a process that may take a year or so as word filters to the traveling masses.